Electromagnetic induction

• What is the topic of the study material?

  Electromagnetic induction
• What factors affect the size and direction of an induced potential difference?

  Magnetic field strength, wire speed, loops
• How does the magnetic field produced relate to the original change?

  It opposes the original change
• What happens to the induced potential difference if the direction of motion reverses?

  The direction of the potential difference reverses
• What is required to create motion against the induced potential difference?

  A larger force is required
• What are the steps in how transformers work?

  1. Alternating current passes through primary coil
  2. Creates a changing magnetic field
  3. Magnetic field is channeled by iron core
  4. Induces potential difference in secondary coil
• Why won't a constant current work in a transformer?

  It creates a stationary magnetic field
• What is the purpose of laminating the iron core in transformers?

  To prevent energy loss due to eddy currents
• What is the relationship between the number of turns in coils and voltage in transformers?

  • More turns in secondary = higher voltage (step-up)
  • Fewer turns in secondary = lower voltage (step-down)
• Why are step-down transformers used for mains electricity?

  To reduce voltage to safe levels
• What is the mains electricity voltage in the UK?

  230 V
• Why is electricity transferred at high voltages in the national grid?

  To improve efficiency by reducing heat loss
• How do transformers help reduce power losses in the national grid?

  • Step-up transformers increase voltage
  • Step-up transformers reduce current
  • Lower current reduces power losses
• What happens to the secondary current in a step-up transformer?

  It is reduced
• What is the relationship between power in and power out for a 100% efficient transformer?

  P1 = P2
• Why are voltages reduced in industrial and domestic situations?

  For safety reasons
• What are the key points about transformers in the national grid?

  • Electricity generated in power stations
  • Transmitted through the national grid
  • Transformers reduce current to minimize losses
  • Voltages adjusted for safety in various applications